The present invention relates to a drive system for hydraulically driven working mechanisms of a working machine and to a method for operating a working system for hydraulically driven working mechanisms of a working machine.
Document EP 2 312 928 A1 makes known a drive system for an infeed conveyor of a harvesting machine. The known drive system comprises an adjustable hydraulic pump, the flow rate and flow direction of which can be adjusted by use of a double-acting hydraulic cylinder. The hydraulic cylinder is controlled by a solenoid valve via a control unit. If a foreign body is detected in the infeed conveyor, the solenoid valve is temporarily controlled by the control unit such that the flow direction is reversed. Such action prevents the hydraulic pump from rotating to a notable extent in the direction of conveyance. A substantial disadvantage thereof is that the pump capacity cannot be limited to zero, due to tolerances in the drive system.
A disadvantage resulting from the actuation of the solenoid valve is that the dynamics by which the solenoid valve triggers a quick stop in the event that a foreign body is detected are insufficient to meet the stringent requirements for operating safety in the event of a quick stop. In order to reverse the flow direction as quickly as possible, the solenoid valve is de-energized in order to quickly degenerate the magnetic field. Subsequent thereto, the solenoid valve is re-energized, thereby activating the neutral position of the hydraulic pump.